Is an rogue-like, adventure game in which you are tasked with exploring the depths of the ocean, trying to find other pockets of humanity.
You start off with your own small submarine just outside the system of caves and air pockets that you grew up in, and have now been sent out to try find other towns and systems with air to trade with for food and supplies for your town. while also exploring for natural resources and avoiding sea creature larger than you.
The world generation will be done proceduraly (similar to FTL) with advances found being available the next time the player launches from home base even if their submarine was lost. Advances will include upgrades to sonar, haul, and weapons capabilities, as well as O2 storage.
The ultimate goal of the game is to be able to find away to the surface again as just trying to go up can be met with dead ends, requiring back tracking and costing Oxygen as well as plenty of deep sea monsters that can take the submarine out.
image source: http://digital-art-gallery.com/picture/13076